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Hybrid MMC Thermal Stress Unevenness Suppression Method Based on Active Bypass and Symmetrical Modulation

A hybrid, thermal stress technology, applied to output power conversion devices, electrical components, AC power input conversion to DC power output, etc., to achieve the effect of reducing thermal unevenness

Active Publication Date: 2020-04-24
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the improvement of the overall efficiency of the hybrid MMC converter does not necessarily mean the improvement of the overall stability of the system, because the heat distribution inside the sub-module has also become an important factor affecting the safe and stable operation of the MMC

Method used

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  • Hybrid MMC Thermal Stress Unevenness Suppression Method Based on Active Bypass and Symmetrical Modulation
  • Hybrid MMC Thermal Stress Unevenness Suppression Method Based on Active Bypass and Symmetrical Modulation
  • Hybrid MMC Thermal Stress Unevenness Suppression Method Based on Active Bypass and Symmetrical Modulation

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Embodiment Construction

[0027] In order to describe the method proposed by the present invention more specifically and clearly, the technical solution of the present invention will be described in detail below with reference to the drawings and specific cases.

[0028] Such as figure 1 As shown, the hybrid modular multilevel converter topology is composed of three-phase six bridge arms, and each bridge arm is composed of N HB Half-bridge sub-modules, N FB A full bridge sub-module and a bridge arm reactor are connected in series. The half-bridge sub-module is composed of two IGBTs, anti-parallel diodes, and DC capacitors. The upper tube IGBTs and diodes use T 1 And D 1 Indicates that the down tube IGBT and diode are respectively T 2 And D 2 Said. The full-bridge sub-module is composed of four IGBTs and anti-parallel diodes. The upper and lower IGBTs and diodes of the left bridge arm use T 1 , D 1 , T 2 , D 2 Indicates that the upper and lower tube IGBT and diode of the other bridge arm use T 3 , D 3 , ...

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Abstract

The invention discloses a hybrid MMC (Modular Multilevel Converter) thermal stress unevenness stabilization method based on an active bypass and symmetric modulation. The method comprises the following steps that: under a working condition that a hybrid MMC normally operates, using a thyristor active bypass half-bridge submodule connected with a half-bridge submodule in series to stabilize the thermal stress of a highest junction temperature device in the half-bridge submodule, and the thermal stress of the highest junction temperature device of a full-bridge submodule can be stabilized through a symmetric modulation method. By use of the method, on a premise that the performance, including the voltage and current output and the like, of the hybrid MMC current converter is not affected, the junction temperature of the highest junction temperature device in the half-bridge submodule and the full-bridge submodule of the hybrid MMC can be obviously lowered, the heat unevenness degree of the internal device of the submodule is reduced, and the method has an important meaning for improving the operation efficiency and service life of the hybrid MMC current converter.

Description

Technical field [0001] The invention belongs to the technical field of power electronic control, and specifically relates to a method for suppressing uneven thermal stress of a hybrid MMC based on active bypass and symmetric modulation. Background technique [0002] Voltage source converter high voltage direct current transmission (VSC-HVDC) based on fully controlled devices has been widely used in island power supply, urban power distribution and large-scale wind power grid connection. In the voltage source converter (VSC) topology, compared with the traditional two-level and three-level converters, the modular multi-level converter (MMC) has better output waveform quality and device switching frequency. The advantages of low and high degree of modularity have become one of the topologies of choice in the field of high voltage direct current transmission (HVDC). At present, most of the MMC-HVDC flexible straight projects are based on the half-bridge sub-module (HBSM) topology. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/757
CPCH02M7/7575
Inventor 李武华盛景杨贺雅李楚杉向鑫罗皓泽何湘宁
Owner ZHEJIANG UNIV